Here’s Part 5 in our Tuesday series: ‘Unconventional Oil Exploration’ – Today we focus on Oil Sands
In this installment on unconventional oils, we’ll discuss oil sands, a resource that plays a significant role in the Canadian oil industry and accounts for the majority of Canada’s total oil reserves.
According to the Alberta Energy website, Alberta’s oil sands have proven reserves of about 168 billion barrels—the third-largest proven crude oil reserve in the world, after Saudi Arabia and Venezuela. The largest oil sand reserve in Canada is the Athabasca. Oil sands are also located in Venezuela, the United States, and Russia.
Oil sands, sometimes called tar sands or bituminous sands, are made up of sand, water, clay minerals, and bitumen, which is heavy, viscous, molasses-like oil that requires extensive processing to separate it from the sand and other materials and refine it into usable fuel. Shallow deposits can be extracted using open pit mining but most oil sand reserves are located too far underground and require unconventional technologies such as steam-assisted gravity drainage (SAGD) and other in-situ techniques to extract and separate the oil.
In the SAGD process, two wells are drilled, one on top of the other. The upper well injects steam into the oil sand formation, raising the temperature, while the lower well collects the bitumen as it becomes fluid enough to be pumped to the surface. See Alberta Energy’s SAGD fact sheet for a detailed description of how SAGD works.
SAGD is the most common extraction method used in Canada but other in-situ technologies, as defined by Alberta Energy include:
- Cyclic steam stimulation (CSS): An in situ method of bitumen recovery that uses steam injection to reduce the viscosity of bitumen deposits, making it possible to pump bitumen to the surface. The process occurs in cycles, with steam injection followed by a resting period, followed by a production phase, then another steam injection and so on.
- Vapor Extraction Process (VAPEX): A gravity drainage process in which solvent vapors are dissolved into bitumen to reduce its viscosity and allow it to be pumped to the surface via a traditional well.
- Toe to Heel Air Injection (THAI): A method of in-situ bitumen recovery in which air is continuously injected into a bitumen deposit to propagate a wave of combustion, which is intended to push recoverable and partially upgraded oil towards a production well or production portion of a well. The name is derived from the initial design of the process; air is injected at the end or “toe” of a horizontal well and the wave travels along the horizontal well length to the “heel.” Once extracted, the bitumen must be “upgraded” into synthetic crude oil by reducing its carbon content or adding hydrogen, or dilution with lighter oils so that it can flow through pipelines to the refinery to be transformed into usable fuel.
Oil sand extraction and refinement processes are among the most complicated, and therefore expensive, especially compared to conventional oil resources. A high return on investment is needed to offset oil sand production costs, making this sector of the oil & gas industry particularly susceptible to fluctuating oil prices. Oil sand production is environmentally costly as well, requiring intensive remediation efforts once mining is completed. These are just a few of the many challenges that mining companies operating in all sectors face. Learn about some of the potential solutions that may ease the way.
Read the entire series: